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skin. Mites of this type are classed as Astigmata, The 

 familiar Gamasus so common on beetles and humble 

 bees, also found from time to time upon the hive bee, 

 possesses breathing tubes whose external openings are 

 placed between the third and fourth pair of legs. Mites 

 of this type are classed as Mesostigmata. Tarsonemus 

 woodi, the parasite of acarine disease in bees, belongs 

 to a group whose males and young forms resemble the 

 itch mites in not possessing breathing tubes, whilst the 

 females have tracheae with a single pair of openings 

 in the anterior region of the body. This group is known 

 us the Heterostigmata on account of this remarkable 

 difference. The term stigmata in these Group names 

 refers to the openings of the respiratory tubes on the 

 surface of the body. 



Recognition Marks of Tarsonemus woodi. 



Under certain circumstances mites of various species 

 may be found in hives, on combs, or upon the bodies 

 of bees themselves. In order to avoid the possible con- 

 fusion in distinguishing Tarsoneynus woodi from other 

 mites I give here some simple particulars regarding this 

 species. Taking the commonest of the cheese mites, 

 Tyroglyphus longior, as a standard likely to be familiar 

 to most readers, I quote first the actual maximum sizes 

 recorded in comparison with those applicable to T. 

 woodi. These are : — 



Cheese Mite, Bee Tracheal Parasite, 



Tyroglyphus longior. Tar.s-onemu,i woodi- 



Millimetres. 

 Adult Female ■•• .75 

 Adult Male 65 



Millimetres. 

 .1.0 

 .15 



This shows that T. woodi is, as near as can be stated 

 in simple figures, just one-fourth of the length of an 

 adult cheese mite. These two types of mite resemble 

 each othei in possessing a delicately thin skin. Beyond 

 this the comparison cannot be carried much further. 

 In habit the one is free living, and relatively active in 

 its movements, the other is an internal parasite. They 

 differ also in many details of structure. Cheese mites 

 have biting jaws (mandibles), bearing a general re- 



